Electric furnace



Jan. 22, 1957 M. C.SANZ EI'AL ELECTRIC FURNACE Original Filed March 24, 1947 ATTQRIJEY United States Patent ELECTRIC FURNACE Manuel C. Sanz, Los Angeles, Carl R. Malmstrom, Whittier, James M. Nuding, Los Angeles, and Hubert P. Yockey, Oakland, Calif., assignors to North American Aviation, Inc.

Original application March 24, 1947, Serial No. 736,630. Divided and this application January 14, 1949, Serial No. 70,822

3 Claims. (Cl. 1320) This application is a division of co-pending application Serial No. 736,630, filed March 24, 1947 in the name of Manuel C. Sanz et al., and covering the process of sealing porous materials utilizing the furnace herein described and claimed.

The present invention relates to a furnace for use in high-temperature sealing of porous materials such as carbon or graphite.

It is therefore an object of this invention to provide a new and novel furnace adapted to operate at extremely high temperatures generally, and which is particularly adapted for use in connection with vapor sealing of porous graphite or carbon.

The invention is illustrated in the attached drawing, which is a sectional view partly in elevation, showing a new and novel furnace used in the process of sealing porous materials.

Referring to the drawing there is illustrated in detail a furnace which is generally usable in instances where a high-temperature, high-pressure furnace is needed.

There is shown in the drawing a casing 20, having detachable end plates 21 and 22, 22 of which is insulated with respect to casing by means of material 50. The casing 20 is preferably circular in cross-section, although other shapes, obviously, may be used. On the interior of the casing there is provided a carbon heating element or rod 23 provided with a passageway 24 therethrough. This rod is made hemispherical at 25 and 26 for engagement by correspondingly shaped ends of electrode elements 27 and 28. Electrode element 27 is carried by member 29 which in turn is fixed to end plate 22 by casing 30 and cap 31. Casing 30 is provided with a water jacket 32 having inlet 33 and outlet 34 for the passage of coolant fluid to maintain the member 29 within an operative temperature range. Electrical lead 49 is attached to plate 22 which serves as a conductor of electricity to rod 23 through casing 36, member 29, and electrode 27. The hemispherical or ball-and-soeket arrangement of the end 25 of rod 23 with electrode 27 provides a satisfactory manner of supporting the rod with freedom from abnormal strain. This arrangement also serves to satisfactorily conduct electricity from the electrode 27 to the rod 23, but at the same time results in a condition of high resistance to passage of heat from rod 23 to electrode 27. This is occasioned by reason of the fact that the relatively poor contact between end 25 and electrode 27, while permitting passage of a satisfactory amount of electricity for the intended purpose, nevertheless creates a high temperature condition which effectively heats the end 25 of the rod and thereby causes the rod to operate more efiiciently, while at the same time prevents the passage of heat from rod 23 to the electrode 27. This condition also obtains at the other end of the rod between end 26 and electrode 28. Electrode 28 is suitably attached to member 35, to which is attached a conductor 36 and a copper bolt 37 adapted to be connected, along with lead 49, to a suitable source of electricity. Member is provided with pasice sageways 38 and 39 for the flow of a cooling fluid, as well as a passageway 40 for the passage of gas to the interior 24 or rod 23. Coolant conductors 41 and 42 and gas conductor 43 pass through end plate 21 and are in turn respectively provided with flexible connections 44, 45, and 46. Member 35 is suitably supported by a spider 47 having associated therewith a closure plate 47a and a bearing 47b in which the member 35 is adapted to slide in response to expansion and contraction of the furnace elements. Springs 48 serve to return member 35, and associated parts, upon contraction of the elements forming the furnace as well as to maintain the electrodes in engagement with the ends of rod 23. The heat from rod 23 is confined and insulated from casing 20 by means of a graphite cylinder or container 51, suitably supported within casing 20 by members 52 and 53. The ends of graphite cylinder 51 are effectively sealed by a plurailty of graphite disks 54 and 55 suitably carried, respectively, by members 52 and 53. Cylinder 51 is also provided with grooves 56 and '57 which serve to minimize transmission of heat by providing a reduced cross-section which limits the quantity of heat that can be transferred. Carbon rod 23 may also be provided with grooves 58 and 59 to reduce transmission of heat to the ends thereof.

The furnace is provided with a plurality of Windows 60, 61, 62, 63, 64, and 65. Each of these windows is formed of a glass holding element 66 adapted to be fastened to a flanged tube 67 which in turn is rigidly attached to casing 20 and about which a cooling coil 68 is adapted to be connected. On the interior of tube 67 there is provided a tube 69 carrying a graphite tube 70 integral therewith and urged into engagement with cylinder 51 by spring 71. Container 51 is provided with an opening 72 to enable observation of the interior thereof by means of a spectroscope, optical pyrometer, or other suitable tem perature measuring device (not shown), suitably associated with the member. Between cylinder 51 and casing 20 there may be provided suitable insulating material B, such as lampblack, or the like.

The casing 20 is also provided with a suitable vent 73 and a drain plug 74 for evacuation or pressurization.

As may be apparent from an inspection of the drawing, casing 20 and associated parts, such as members 47a, 52, and 53, and end plate 22, are provided with cooling coils 75, 76, 77, and 78, respectively. Windows 60, 61, 62, 63, 64, and 65 are also provided with cooling coils such as coil 68 associated with window 60, and coil '79 associated with the tubing 69. The remaining windows are provided with similar cooling coils. Outer cooling coils are adapted to cool the casing. It is to be understood that the cooling coils are connected to a suitable source of coolant fluid which may be caused to flow therethrough by any suitable means, not shown.

In use of the furnace for carrying out the sealing of carbon by sublimation, a hollow tube, such as 23 may be sealed in a manner similar to that described in application Serial No. 736,630, of which this application is a division. If desired, the furnace may be used merely as a high-temperature, high-pressure furnace. A shielding member surrounding the tube 23 may of course be used in connection with this furnace if so desired, although it is not ordinarily necessary in view of the use of the graphite container 51 and the lampblack insulating material. When a porous substance is to be used in conjunction with atomic energy material, it may be first impregnated with an active substance. However, it is to be understood that the impregnation may take place after partially sealing, it so desired.

The furnace may be utilized for testing materials at high temperatures by, for instance, attaching member 23 to members 27 and 28 by screw connections, removing cap 31, and replacing member 29 with an elongated mem ber adapted to be subjected to tensile forces. It will be necessary, of course, to fasten member 35 to bearing 47]) by suitable means such as a clamping screw or the like. By so utilizing the 'furnace the adaptability of various mater ials for use in reactor pile construction may be readily investigated.

Although the invention has been described and illustrated in detail, it is to be clearly understood that the same is by Way of illustration and example only and is not to be'taken by way of limitation, the spirit and scope of this invention being limited only by the terms of the ing, a container located interiorly of said casing and supported in spaced relation thereto, insulating means between said casing and said container, a carbon element in said container, and electrodes carried by said casing, one of which is insulated with respect to said casing and the other of which is slidably supported thereon, the ends of References Cited in the file :of this patent UNITED STATES PATENTS 319,945 Cowles et a1 June 9, 1885 1,513,890 Bryant et al. Nov. 4, 1924 1,594,000 Breyer July 27, 1926 1,689,224 Bishop Oct. 30, 1928 1,884,600 Derby Oct. 25, 1932 1,897,004 Heyroth Feb. 7, 1933 1,951,753 George et al. Mar. 20, 1934 1,980,825 Rankin Nov. 13, 1934 1,989,736 Boyles Feb. 5, 1935 1,997,622 Benner etal ,Apr. 16, 1935 2,219,615 Berghaus et al. Get. .29, 1940 2,251,380 Warrender Aug. 5, 1941 2,268,691 Brooke Jan. 6, 1942 2,476,916 Rose et al July 19, 1949 FOREIGN PATENTS 552,234 Great Britain Mar. 29, 1943 

